Patent GB-491954-A (GB)
Title: Improvements in or relating to method of and apparatus for annealing glassware
IPC: C03B25/06
Filed: 1936-12-11
Abstract: 491,954. Glass annealing leers ; burners. HARTFORD-EMPIRE CO. Dec. 11, 1936, Nos. 34084 and 34085. Convention dates, March 2 and Sept. 22. [Classes 51 (i) and 51 (ii)] [Also in Group XI] Relates to tunnel glass-annealing leers in which the tunnel atmosphere is circulated to produce and maintain the desired temperature gradient, and comprises arrangements in connection with the heated entrance zone, in which the ware is brought up to annealing temperature, for circulating the tunnel atmosphere in a direction lengthwise of the leer, and in connection with the succeeding zone, in which the ware passes through its critical annealing range, for circulating the atmosphere in a transverse direction, the path of flow being from the middle to the sides below the ware conveyer, up the sides of the tunnel, back to middle, and then down through the ware. A transverse circulation of the tunnel atmosphere is also maintained in the cooling section, and throughout the leer the temperature conditions in one half of the width can be controlled independently of those in the other half. In a gas fired leer in which the products of combustion are brought into contact with the ware, the entrance section (Figs. 1, 8 and 15) is fired by four burners 36 arranged beneath the conveyer 22 and connected to a combustible mixture supply in pairs. These burners deliver towards the entrance end through arched burner blocks 42 and Venturi passages 43, at the ends of which arc dampers 50, 51, 52 (shown diagrammatically in Fig. 8 as a single damper 53) for controlling the proportions of combustion products which are exhausted to atmosphere through the grating 47 in front of the door 35, and passed into the tunnel behind the door. The passages 43 are roofed by refractory tile 44 adjacent the burners, and further on by ribbed heat-radiating metal plates 45. In operation the burners 36 induce a downward flow of the tunnel atmosphere for recirculation with fresh combustion products, surplus gases being allowed to escape through the grating 47, where they serve to prevent entrance of cold air to the leer. The three dampers 50, 51, 52 are connected by hinged rods 55 to a transverse bar 56, Fig. 15, having end pins which can be inserted into any one of a number of holes in brackets 58 so that a simultaneous and, if desired, differential adjustment of the dampers can be effected. The main annealmg-zone, of which a small part only is shown in Figs. 1 and 8, is fired by six burners 59 each having four nozzles 68 .. 71, Fig. 16, delivering at an angle of 45‹ to the axis of the leer, the pairs of nozzles delivering to the two sides of the leer being fed by separate pipes 60, 61 connected to chambers 66, 67 in the body 65 of the burner. The metal parts are protected by refractory material 72, 73 and the burner is formed on its underside with a locating stud, which fits a corresponding recess in a floor block. Each nozzle delivers through a burner block 83 into a combustion chamber 86 formed by the leer floor, a side wall 15, blocks 76, 88, 89, and cover blocks 93, 95, the latter being arranged to leave a gap 97 adjacent the side wall through which the products of combustion can pass upwards into contact with the ware. Recirculation of the gases is effected by the inductive action of the burners. At the inner end of the heated annealing-zone may be a short section which is neither heated nor cooled, and beyond this is a cooling section of which part is shown in Figs. 5 and 13. Extending the length of this section at the upper corners of the leer chamber are air supply pipes 99 fed under damper control, by a blower, and having interchangeable nozzles 107, some of which deliver normally to the axes of the pipes, while others are inclined towards the entrance end of the leer, the latter nozzles preferably being employed adjacent the delivery end to induce an inflow of air. The air from the nozzles impinges on deflectors 118, and is directed downward through the ware, after which it flows laterally and is recirculated by the inductive action of the jets. In the first part of the cooling-zone the deflectors 118 form part of a long trough 112 having its upper edges spaced from the roof to leave gaps 119 through which the cooling-air is exhausted to an outlet port 120 under control of simultaneously-operated dampers 121, 122. Following this are six independent ports 133, outflow through which is controlled by pivoted dampers 131 at the upper edges of the deflector plates, and a final short section with no outlets for air. In operation the air in the cooling-zone moves in two helical paths in a general direction counter current to the ware, and the various dampers controlling the exhaust of air are normally so adjusted that the volume of air in circulation becomes progressively less towards the hotter end of the zone and that there is little or no flow of air to the annealing-zone, or of combustion products to the cooling-zone. When preheating the leer, however, or when light articles are being annealed, the positive cooling may be reduced or stopped, and part or all of the combustion products may be exhausted through the ports 120, 133. In a modification, Fig. 20, the air supply pipes 99a are rotatable through a small angle and each nozzle 107 delivers on to the inclined meeting- edge of two deflectors 141, so that by adjustment of the pipe the entering air can be directed towards the entrance or exit end of the leer as may be desired. The muffle leer shown in Figs. 21-23 is fired by a single burner 213, Fig. 23, delivering into a combustion chamber 212 in communication through the opening 214 with a chamber 213A beneath the forward end of the leer chamber, and separated therefrom by a corrugated heatradiating wall 216. Air for secondary combustion is supplied through the port 227<1>, and a baffle 215 in front of the opening 214 directs the gases to the sides of the chamber 213A from which they are exhausted through pipes 220 in heat-exchanging relationship with the main annealing zone, and damper-controlled uptakes 225 fitted with independently-controlled air ejectors supplied from a fan 234. This fan also supplies air to heating pipes 237 arranged within the exhaust pipes 220 and leading to a two-part header 238 having forwardly-directed nozzles 241 delivering between the roof 216 of the chamber 213A and the ware conveyer. The jets from these nozzles maintain a longitudinal circulation of the atmosphere within the entrance zone of the leer. In the annealing- zone the transverse circulation is maintained by jet nozzles 245 on two pipes 244 leading from the two parts of the header 238. Surplus air escapes from the entrance end of the leer. The cooling-zone arrangements are the same as those previously described with the exception that an additional outlet port 258 is provided. The tunnel structure comprises an inner lining of floor blocks 14, Fig. 1, side wall blocks, and roof blocks 16, an outer metal casing carried by a suitable framework, and an interposed filling 20 of heat-insulating material. The lining blocks are preferably made of a calcined diatomaceous earth concrete, and the roof blocks are cast with bracket members 17 by which they can be hung from the outer framework. The conveyer 22 is of the woven wire type and moves in the heated zones over sectional supports, each unit of which comprises longitudinal channel members 25, Fig. 1, transverse angles 26 welded thereto, and side Z-bars 27 for positioning the conveyer band. In the cooling-zone the supports 30, Fig. 5, are secured to the bottom plate 29 which is in turn anchored at one point only to the framework by means of transverse angles on its under side arranged to straddle a cross member of the frame. Specification 487,227 is referred to.